The present invention relates to a semiconductor element and then particularly to an improved semiconductor element especially for use in a transistor.
U.S. Pat. No. 5,146,298, for example, teaches a semiconductor element, particularly a high-voltage MOS-transistor, that includes a substrate of a first conductive type on which there is mounted a layer of material of a second conductive type that includes cells which are comprised of material of a first conductive type in which the electrical contact areas, source area and gate area, are placed and also an electric contact area of a second conductive type, drain area. According to this prior publication, the first type of conductive material is normally p-type silicon doped with about 5×1014 atoms per cm3, whereas the second conductive material is n-type silicon doped with about 3×1012 atoms per cm3. A further area formed by two layers of the first and the second conductive types of material respectively is disposed between drain area and the other two contact areas. The substrate has a typical thickness of from 100 to 500 μm. An effective breakdown voltage of about 300 V is obtained with these dimensions and doping levels. The semiconductor element also includes an insulating outer layer through which the electric contacts extend.
The object of the present invention is to provide an improved semiconductor element of this type, in which the dimensions of said semiconductor element can be reduced substantially without detracting from its performance.